The commonly used clinical indicators to evaluate glomerular filtration function, such as serum urea nitrogen (BUN), serum creatinine (Scr) and endogenous creatinine clearance (Ccr), have certain limitations and are affected by some other factors to varying degrees. Cystatin C is a new endogenous index of glomerular filtration rate (GFR) that has been reported in recent years. Compared with Scr and Ccr, Cystatin C is a more accurate and reliable indicator of GFR, which is valuable for the early diagnosis of patients with various acute and chronic kidney diseases.